This invention relates generally to the field of chemical processing, particularly processing of toxic volatile or otherwise dangerous substances, and more particularly to an improved process sampling system by means of which small quantities of substances to be examined may be removed from a reacting mass for analysis at convenient intervals during a processing cycle. Devices of this general type are known in the art, and the invention lies in specific constructional details which afford increased convenience with regard to the recycling of a tested sample, and, more importantly, increased safety to the technician or operator conducting the sampling operation.
The need for obtaining uncontaminated representative samples of chemical processing operations has been one of long-standing. The most common method employed involves the use of a so-called dip tube which is projected through or mounted within an orifice in the reactor vessel. Where the sample material is not particularly dangerous, this structure has proved adequate.
More sophisticated sampling devices include those sold under the trademark DOPAK. These devices include a means for connecting into the process line at a suitable point which means includes a valve to control flow to a sample container. Adjacent to the valve is a pair of hollow needles, both of which penetrate a self-sealing diaphragm or septum located beneath the threaded cap of the sample container. One needle feeds the sample, while the other needle exhausts air or other displaced fluid within the container. When the container is filled with the sample to desired volume, the container is disconnected from the needles without spillage.
Another type of sampling device is market under the trademark POSACON. This type of device is installed in line with a conduit, and includes a transversely extending needle valve which communicates with a selectively engageable piston injector which operates somewhat in the manner of a hypodermic syringe. The injector has means for closing the same against leakage before disconnecting from the valve body.
In both types of devices, above described, after examination and/or testing of the sample, there remains the problem of disposing of the unused portion thereof which may create environmental problems, particularly where the samples are corrosive, toxic, or otherwise dangerous.
In the above identified co-pending application there is disclosed a sample valve construction which provides for collection of a sample from a process line into a sample container and the disconnection and removal of the sample container from the valve for analysis of the contents. The sample container is removable only after it is placed in closed condition, and the user must open the closure in order to gain access to the collected sample, usually by unthreading the container from the closure element to prevent manipulation of the cover plate overlying the opening in the neck of the container. Once the required sample has been removed for analysis, the remainder of the sample can be returned to the process line, thereby simplifying disposal. In the case of samples obtained under pressure, substantially above atmospheric pressure, use is made of an optional safety enclosure through which visual observation of the collection of the sample may be made without risk to the technician.
In the above-described structure, however, it is possible for the technician to accidentally unthread the container or bottle from the engaged bottle closure while the latter is still engaged with the sample valve structure with the possibility of spillage of at least a part of the then collected sample. This might occur, for example, when the threaded engagement of the bottle is more easily dislodged than the bayonet engagement of the bottle closure with the sample valve structure. Another difficulty has been experienced in the case where it is desired to extract a part of the collected sample by means of a hypodermic syringe or the like through a self-sealing membrane without the need of uncovering the openings in the cover plate, this type of extraction being particularly desirable where the quantity of the required sample is relatively small, and the potential danger in handling the sample is significant.